Vehicles typically have various control systems that operate and control the use of vehicular components. For example, one vehicular control unit controls the operation of the steering wheel. Steering wheel control units typically receive signals from users and sensors and utilize these signals to operate (e.g., turn) the steering wheel as the operator of the vehicle drives their vehicle.
The operation of the above-mentioned control units often depends upon or is directly or indirectly related to the angular position of the rotor of the motor. If this position cannot be determined accurately, then the control unit will not operate the vehicle component properly. In the case of a steering system controller, an inaccurate rotor position may cause the unit to be operated erratically resulting in steering problems for the vehicle and inadequate performance for the occupant of the vehicle.
Various approaches have been used to attempt to determine accurate rotor position such as using Hall sensors to measure the magnetic field transitions caused by a rotating magnetic ring associated with the rotor. However, to obtain accurate readings of the rotor position, a relatively large number of these sensors were required. Since Hall sensors were expensive to install and maintain, their usage increased the cost of the system. Further, the algorithms that are used to determine the rotor position were typically complicated and some times not very accurate. Consequently, the cost, complexity, and/or unreliability of previous approaches has led to general user dissatisfaction with these previous approaches.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.